Project 5 proposes to test whether exposure of vascular endothelium to the HIV-1 can alter normal function of the endothelial cells (EC). It has been reported that cells expressing the HIV-1 tat gene product may indirectly affect apparently uninfected EC. Because of the complexities of these questions and possible co-founders, an in vitro model system will be developed for the exposure of EC to HIV-1 using human fetal EC. Using data obtained from these experiments, CNS tissue from infected and uninfected abortus tissues will be compared for alterations in phenotype as well as for differences in cytokine and growth factor gene expression.